Mephobarbital

Mephobarbital (N-methylphenobarbital) is a long-acting barbiturate that is N-demethylated in the liver to phenobarbital, which contributes significantly to its anticonvulsant effect. Like phenobarbital, it enhances GABA-A receptor-mediated inhibition by prolonging chloride channel opening duration. The 5-phenyl substituent on the barbituric acid ring is responsible for anticonvulsant selectivity over sedation, allowing therapeutic use at sub-hypnotic doses.